This invention relates to the interconnection between two or more electrical layers on opposing faces of an optical structure of an integrated optical circuit, and provides a scheme for obtaining electrical interconnection between the electrical layers to enable denser component layout and consequently a higher degree of component integration on a single substrate. In certain embodiments, the electrical interconnect function is combined with an optical function, such as an out of plane reflector.
In integrated electrical circuits, the use of electrical interconnects (vias) through electrically insulating elements to connect electronic and electrical elements otherwise separated by the insulating element is known in the prior art. Electrical vias are typically prepared by creating holes in the insulating elements that separate the electronic/electrical elements to be connected, applying a conductive metallization layer to the surfaces of the holes within the insulating layers, and finally patterning the metal layer to ensure an electrical pathway between this metallization layer within the holes and the electronic/electrical elements being connected through the insulating element. The diameter of the holes must be consistent with the electrical current being carried and the resistivity of the metallization layer.
Paralleling the history of the integrated electrical circuits (IC""s), integrated optical devices are shrinking in size even as the number of functional elements in the devices increases. This increasing density creates problems in the design and subsequent manufacture of such devices. Consider now the situation with electrical interconnection between and among integrated optical and electrical components.
Previously, in integrated optical devices, individual components and devices have been demonstrated which are typically electrically connected by the use of surface probes or edge connectors. Such coupling techniques are only possible with the low level of integration of electrically activated integrated optical components that has previously been contemplated. As the complexity of the integrated optical circuit increases and the density of the electrically activated components increases, it eventually becomes impossible to lay out the electrical connections in a single conducting or electrical layer.
It would therefore be advantageous if the use of surface probes or edge connectors could be replaced by an alternative connector which would save valuable surface space, and if other elements in the integrated optical device could also function as vias. Design options would increase, and manufacturing processes (costs) would be reduced.
Integrated optical devices find widespread and practical uses in many industries including the communications industry and the flat panel display industry. There are functional reasons why some elements have to be placed in certain critical relationship to one another. In some devices, certain elements must be separated by minimum distances. For example, electrical elements can xe2x80x9cshortxe2x80x9d if too tightly spaced, and similarly optical elements can unintentionally couple if too tightly spaced. Conversely, in some devices, some elements must be in very close proximity and alignment one with another. For example, electrically operated optical waveguide switches require a critical spatial relationship with the waveguides they control. The increasing density and limitations on the layout of electrical and optical elements both lead to the desire to use alternative electrical interconnect techniques. In some cases, the desired component density will not be achievable without putting optical/electrical components in multiple layers.
Another route to higher density and facilitating the layout of the various elements is through the use of multi-functional elements. Space can be saved and manufacturing processes simplified or eliminated if one element can fulfill two or more functions, increasing design options and reducing cost.
The manufacturing process for electrical interconnect vias is currently seen as a distinct process consisting of multiple steps. In addition, only a limited space may be available for vias to connect or pass through two or more layers, which may contain multiple optical elements which may severely restrict the available pathways for the vias to occupy.
The present invention addresses this need and other needs as described in the following description.
In one aspect, the invention comprises an optical device. The device includes at least first and second electrical conductors. At least one optical layer overlies at least a portion of said first and second electrical conductors. An applicator is positioned proximate to said at least one optical layer to selectively redirect light from or within said optical layer in response to a control signal. An electrical coupling path is provided between said at least one applicator and one of said first or second electrical conductors, at least a portion of the electrical coupling path traversing at least a portion of said one optical layer.
In a further aspect, the invention comprises a display in which at least one optical waveguide is formed in an optical layer above said electrical conductors. At least one feature is located to receive light redirected from the waveguide by the action of the activated applicator; and at least one electrical coupling path included in said feature couples the applicator and at least one of said plurality of conductors.
In accordance with the invention, the optical layer may comprise a first cladding layer and a second cladding layer on opposing sides of a core layer.
In various embodiments of the invention, the feature may comprise: a pixel; an optical redirector; an optical re-emitter; an optical re-radiator; a thermal conductor; a via formed in said optical layer, or a combination thereof.
In further embodiments of the invention, the applicator may comprise a heating element for a thermo-optic switch or control an optical redirector which operates by reflection. Still further, said applicator may control an optical redirector which operates by suppressing or inducing waveguiding properties in an optical waveguide.
In yet another embodiment, the invention comprises a method for manufacturing an optical device. The method comprises the steps of providing a substrate; constructing at least a first electrical conductor in a first substantially planar layer; forming an optical guiding structure in an optical layer; constructing at least one applicator; constructing a feature; and forming an electrical coupling path between the applicator and said at least first electrical conductor.
In further embodiments, the invention includes forming the electrical coupling path in the feature, and/or forming said electrical coupling through the optical layer.